Detection rules › Splunk
Suspicious Parent Process for lsass.exe or services.exe (Windows Event Log)
This use case detects when either the Windows local security authority subsystem (lsass.exe) or service control manager (services.exe) are executed as a child from an unexpected parent process. This can indicate process injection/hollowing, masquerading, or other suspicious activity. The expected parent process for these services is wininit.exe.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Privilege Escalation | T1055 Process Injection |
| Stealth | T1036.004 Masquerading: Masquerade Task or Service, T1055 Process Injection |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '16171.24332'
title: Suspicious Parent Process for lsass.exe or services.exe
description: This use case detects when either the Windows local security authority
subsystem (lsass.exe) or service control manager (services.exe) are executed as
a child from an unexpected parent process. This can indicate process injection/hollowing,
masquerading, or other suspicious activity. The expected parent process for these
services is wininit.exe.
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) ("lsass.exe" OR "services.exe") | regex process_path="(?i)\x5csystem32\x5c(lsass|services)\.exe"|
regex parent_process_name!="(?i)wininit\.exe"| where isnotnull(parent_process_name)
and not match(parent_process_name, "^-$") | table _time, host, user process, process_*,
parent_process_name, parent_process_* | bin span=1s | stats values(*) as * by _time,
host '
techniques:
- defense-evasion:masquerading:masquerade task or service
- defense-evasion:process injection
technique_id:
- T1036.004
- T1055
data_category:
- Windows event logs
references:
- https://andreafortuna.org/2017/06/15/standard-windows-processes-a-brief-reference/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) ("lsass.exe" OR "services.exe")
Stage 2: regex
| regex process_path="(?i)\x5csystem32\x5c(lsass|services)\.exe"
Stage 3: regex
| regex parent_process_name!="(?i)wininit\.exe"
Stage 4: where
| where isnotnull(parent_process_name) and not match(parent_process_name, "^-$")
Stage 5: table
| table _time, host, user process, process_*, parent_process_name, parent_process_*
Stage 6: bucket
| bin span=1s
Stage 7: stats
| stats values(*) as * by _time, host
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
parent_process_name | regex_match | "(?i)wininit.exe" |
parent_process_name | match | "^-$" |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
parent_process_name | is_not_null | |
process_path | regex_match |
|
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | "<EventID>4688<" |
| 1 | "lsass.exe" |
| 1 | "services.exe" |